1. Field of the Invention
The present invention relates generally to a paper discriminator for discriminating papers such as bills, and more particularly, to a paper discriminator provided with a line sensor detecting the entire surface of paper being conveyed and with a point sensor detecting a part thereof.
2. Description of the Related Arts
Paper handling apparatuses such as ATMs (Automatic Teller Machines) for processing, e.g., deposits and payments of bills incorporate a bill discriminator arranged to identify plural types of bills loaded or discriminate between the true and false of the bills loaded.
FIG. 4 is a diagram for explaining a placement of a line sensor and a point sensor in the bill discriminator. As shown in FIG. 4, the bill discriminator has the line sensor for taking images of the bills in a conveyance path, and the point sensor (for example, a magnetic head) for detecting a predetermined physical amount (for example, a magnetic amount) of the bills at a position away from the line sensor by a distance L. The line sensor is arranged in a direction (X direction) perpendicular to a conveyance path direction (Y direction) of the bills, and the bills pass the line sensor, so that the line sensor can take images of the entire bill. Furthermore, the bills pass the point sensor (for example, a magnetic head), so that the point sensor detects a physical amount (for example, a magnetic amount) of a part (1 line) of the bills.
Generically, a bill loading port of the bill processor has flexibility of about 20 mm with respect to a width of a bill, and a width of the conveyance path is wider than that of the bill. Accordingly, it is not limited that the bill is carried in parallel to the X, Y directions, and is occasionally carried obliquely to the line sensor.
FIGS. 5 are diagrams for explaining a conventional bill discrimination method. FIG. 5A is a typical view of image data of the bills carried in an inclined state on a XY coordinate plane. A data procession part of the bill discriminator detects an end point A of the bill and the inclined angle θ from the taken images by a predetermined data procession, and moves and rotates with the home position O as a reference, thereby executing the image data of the bill normalized as shown in FIG. 5B. The normalized image data move and correct a rotation, whereby the bill images approach a left corner, and are paralleled to the X, Y directions. The bill discriminator has in advance stored the image data (dictionary data) of intrinsic bills in a state that they are paralleled to the X, Y directions, and compares such dictionary data with the normalized image data, thereby judging a type and a truth or falsehood of the bills.
On the other hand, data obtained from the point sensor become a piece of linear data, as shown in FIG. 5C. For example, in the case where the point sensor is a magnetic head, the magnetic head detects magnetism included in an ink in a bill part passing it, thereby obtaining the magnetic data in a part of the bills. However, as described above, when the bills are carried in an offset manner, as it does not detect the entire bill unlike the line sensor, it cannot be judged which part of the bill the obtained magnetic data detect. Accordingly, as the detected magnetic data cannot be compared with the magnetic data of the intrinsic bill, in the prior art, a gross integration value of these magnetic data is acquired, etc. which is exploited for a truth or falsehood of the bill based on presence or absence of a magnetic amount, or the amount.
However, when it is possible to specify which part of the bill as data corresponds to the obtained magnetic data, it becomes possible to compare them with the magnetic data of the intrinsic bill, and to discriminate with higher precision.
On the other hand, a plurality of magnetic heads are arranged in an X direction, thereby configuring the line sensor, and the same correction processing as in the image processing in the above optical type line sensor is made, whereby it becomes possible to compare with the magnetic data of the entire intrinsic bill, and as causing an increase in costs, the configuration is not realistic.